1. Field of the Invention
The present invention relates to a bonding device for manufacturing a vehicle seat such as an automotive seat, and particularly relates to an improvement of a bonding device for bonding a top cover member to an unvenly-shaped surface of a foam cushion member (made of urethane foam material).
2. Description of the Prior Art
In a conventional process for manufacturing a vehicle seat, bonding a top cover member to a foam cushion member is effected by such bonding device as shown in FIG. 1 so as to provide a seat shown in FIG. 2. According to this prior art device, lowering and pressing of an upper die (a'), on which a foam cushion member (1) is secured, against a top cover member (2) placed on a lower die (b) so that the top cover member (2) is bonded to the cushion member (1) via an adhesive.
But, the fact that the cushion member (1) is formed unevenly on its upper surface as in FIG. 2, namely, formed with a raised bolster portion (11) at its both sides, a central portion (12) defined between the raised bolster portions (11), and a recessed groove (13) at the top of each bolster portion (11), creates a difficulty in neatly bonding the top cover member (2) to the upper surface of cushion member (1) and, in particular, at the recessed grooves (13), which serve to produce decorative dents (2a) on the top cover member (2) for aesthetic purpose, the complete bonding of the cover member (2) thereinto is not practically effected, increasing the possibility that the corresponding portions of cover member (2) will be easily peeled from the recessed grooves. (13). This difficulty arises from a poor pressure distribution caused by the thickness variations in the cushion member (1). That is, the central portion (12), whose thickness is relatively thin, is applied a pressure from the upper die (a') at a sufficient degree to be bonded with the corresponding portion of the top cover member (2), but the raised bolster portions (11), whose thickness is much greater than the central portion (12), is not sufficiently applied the pressure from the upper die (a'), as a result of which their corresponding portions of the cover member (2) are not fully bonded to the bolster portions (11). The same applies for the respective inner lateral surfaces (14) of the bolster portions (11), and particularly applies in the case where the inner lateral surfaces (14) extend substantially in alignment with the direction of the pressure applied thereto by the upper die (a').